/***************************************************************************
 *   Copyright (C) 2005-2008 by the FIFE team                              *
 *   http://www.fifengine.de                                               *
 *   This file is part of FIFE.                                            *
 *                                                                         *
 *   FIFE is free software; you can redistribute it and/or                 *
 *   modify it under the terms of the GNU Lesser General Public            *
 *   License as published by the Free Software Foundation; either          *
 *   version 2.1 of the License, or (at your option) any later version.    *
 *                                                                         *
 *   This library is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU     *
 *   Lesser General Public License for more details.                       *
 *                                                                         *
 *   You should have received a copy of the GNU Lesser General Public      *
 *   License along with this library; if not, write to the                 *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA          *
 ***************************************************************************/

// Standard C++ library includes
#include <cstdio>

// 3rd party library includes
#include <png.h>
#include <SDL.h>

// FIFE includes

int write_png(const char *filename, SDL_Surface& surface) {
	FILE *file = fopen(filename, "wb");
	if (!file)
		return -1;

	png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!png_ptr)
		return -1;

	png_infop info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr) {
		png_destroy_write_struct(&png_ptr, NULL);
		fclose(file);
		return -1;
	}

	if (setjmp(png_jmpbuf(png_ptr))) {
		png_destroy_write_struct(&png_ptr, &info_ptr);
		fclose(file);
		return -1;
	}

	png_init_io(png_ptr, file);

	png_set_IHDR(png_ptr, info_ptr, surface.w, surface.h, 8, PNG_COLOR_TYPE_RGB_ALPHA ,
			PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);

	/* does this leak memory? */
	png_byte** row_pointers = (png_byte**)png_malloc(png_ptr, surface.h * sizeof(png_bytep));
	
	png_byte* p = (png_byte*)surface.pixels;
	for (int i = 0; i < surface.h; ++i) {
		row_pointers[i] = p;
		p += surface.pitch;
	}

	png_set_rows(png_ptr, info_ptr, row_pointers);

	png_write_png(png_ptr, info_ptr, 0, NULL);

	return 0;
}